Hypodermic injector



July 31, M LOCKHART 2,380,534

HYPODERMIC INJECTOR Original Filed April 26, 1941 I m3 jf /a l ya Patented July 3 1, 1945 HYPODERMIC INJECTOR Marshall L. Lockhart, Detroit, Mich.

Original application April 26, 1941, Serial No. 390,598. Divided and this application March l5,

1943. Serial No. 479.183'

5 Claims. (Cl. 12S-215) My present invention relates to a hypodermic vinjector which does not require the use of a hollow needle to accomplish injection, this application being a division of my copending application, Serial No. 390,598, filed April 26, 194i, now Patent No. 2,322,245, issued on June 22, 1943.

One object of the present, invention is to provide hypodermic injector mechanism of simple, durable and inexpensiveconstruction.

Another object. is to provide a hypodermic in- ,lector which eliminates the necessity of using a hollow needle and the usual type of syringe in conjunction therewith, yet which effectively injects liquid or medicants, such as novocain. antiseptic and the like into animal tissue, leaving only a microscopic scratch on the surface of the tissue.

More particularly, it is my object to provide a hypodermic injector containing an ampule in which the liquid to be injected is enclosed, and means capable ot exerting a predetermined high pressure within the ampule `(which exceeds approximately 30 atmospheres, or 400 pounds per square inch) by suitable means, such as a spring or compressed air biased plunger to displace the liquid from the ampule through a discharge oriiice. such orifice being so minute that the liquid is vaporized or atomized so finely that it can pass through animal tissue, leaving a hole therethrough large enough to be seen only through a microscope. thus eliminating the risk of infection, fright, pain, etc., of the usual hypodermic needle, the o'nly feeling of the patient being the sensation of a slight breeze blowing against the skin as the injection takes place.

Another object is to provide a hypodermio injeotor wherein a predetermined and substantially instantaneous build-up oi pressure may be secured for the purpose of predetermining the force of ejection of the liquid, thus securing precision control of dosage and administration of the liquid to the hypodermic location desired.

Still a further object is to provide a hypodermio injector using a compressed spring, compressed air or the like as motive power for driving a plunger against a follower with an impact blow,

whereby the follower displaces the liquid from the ampule of the injector, and to further provide such a device which is suitable from a commercial standpoint, and makes it possible to provide a physician with different quantities of liquid to' be injected, and a readily selectable supply oi injec.

tions to suit his particular needs. I

Finally, itis an object oi my present invention to make an injector mechanism which is spring or compressed air operated, which has but few parts, and these parts soarranged as to facilitate their assembly with relation to each other to form the completed injector mechanism.

With these and other objects in view. my invention consists in the combination, constructionl and arrangement of the various parts of my device whereby the objects contemplated are attained. as hereinafter more `fully set forth, pointed out in my claims and illustrated in the accompanyng drawing, in which:

Figure lis a'longitudinal sectional view through one form of my invention, showing a spring to effect the build-up of pressure necessary .to force the hypodermic liquid from the injector with injection force, the spring being shown in contracted-position, as when the device is cocked; Figure 2 is a similar sectional view oi Figure l. showing the spring released and having elected discharge of the hypodermic liquid; and

Figure 3 is a similar sectional view of a modified form wherein compressed air ls usadas the propelling force.

On the accompanying drawing, I have used the reference numeral Si to indicate a cylindrical ampule containing hypodermic liquid 92 to be injected. One end ci the ampule 9| is provided with a discharge orifice 93 which is of very minute size. I have found that between .001 and .006 inch are suitable sizes for the purpose, although other szes, of course, can be used to suit the particular requirements of the injection to be made. The size of the discharge orifice 93 is much smaller than the area within the cylinder 9|. which area is illustrated about full size in Figure l, whereas the orice 93 is necessarily enlarged in a. cylinder 95, in which a plunger 96 is slidably mounted. The plunger has a reduced portion 9F and a head 98. A stem 99 extends from the head 98 through a cap nut |60 in the outer end of the cylinder 95. An actuating knob lili is mounted on the stem 99, and a sprine.r |02 is interposed between the plunger head 98 and the cap nut |00.

A latch pin |63 is s lidably mounted transversely in the cylinder 95, and ls biased to the latching position shown in Figure 1 by a spring IM. The plunger 98 andits reduced end 9T are adaptalato move through a bore |05 in the latch pin In the operation of the injector shown in Figures 1 and 2, the knob IUI may be grasped and pulled outwardly from the position of Figure 2 to the position of Figure l. The spring |08 will cause the latch pin |03 to assume the position ly, as to the position or Figure 2, the plunger- 90 will be released as soon as the opening |09 resi' isters with it, and the spring |02 will lexpand,V

thereby causing the reduced end 91 to strike the .z

follower 90 and then force it forwardly in theV bore of the container of the ampule 9|. This will cause the hypodermic liquid 92 to be. displaced through the orifice 93 with suiiicient force to accomplish hypodermicinjection. Such force,as already mentioned, must be in excess of 400 pounds per square inch, produced on the plunger 90, and. consequently, on the liquidv 99, .before injection to a hypodermic position can be successiully accomplished.

In Figure 3 there are many parts similar to.

those described in Figures l and 2, and they bear the same reference numerals.- Other parts involved will now be described.

.The plunger 90 carries a piston |00 slidable in a cylinder 95i which is larger than the one shown in Figure l. Means is provided for building up a chargeof highly compressed air in the cylinder 95B, and may consist of a second piston lul, a piston rod |08 therefor, and a rod |09 for operating the piston |07. The knob |09 has-a threaded part lili adapted to coact with threads |62 of y the cylinder 95a. 4

In the operation of the device shown in Figure 3, the knob |09 is unscrewed at iid-iig,

and the piston |0l pulled outwardly, which also pulls the piston |06 outwardly, causing it to be locked, Aas illustrated. 'I'he piston lill is then pushed inwardly and locked in its inward posiu tion by engaging the threads' l 0 with the threads H2. This contines a charge of highly compressed air between the pistons |06 and |07, whereby, upon depression of the latch pin |03, the plunger 98 is released so that the air acting on the piston |06 will force the plunger forwardly and result in the reduced .portion 91 of the plunger striking the follower and propelling itforwardly.

AIl() makes the area about 1/40 of a square inch.' It is therefore obvious that a pressure of 25 pounds' initial build-up (almost instantaneously) of the y' pressure isA sufcient to cause the liquid to be 4expelled in a very line stream and with sufilcient force to cause it to penetrate through the skin of the patient being treated. Thepenetration produces a minute opening through which the yremaining liquid can follow without as much pressure as is necessary for tion by the liquid. f

l My hypodermic injectoreliminates the necessity oi mechanically puncturing the Itissue in order to inject a medicant into-it. It also elimithe initial penetra,-=

nates the pain and fright attendant on an in- 1 jection of theneedle type.

The method involved comprises the steps oi enclosing the fluid to be hypodermically injected in such manner that a movable wall of the con tainer'for the liquid may be relatively quickly forced into the container by the force of a spring or other biasing means assisted by impact, so that the result is expulsion of the liquid in a streamcontrolled form; Claims covering the method will be found in my Patent No. 2,322,245, hereinbefore mentioned.

With either type of injection mechanism, the r operation occurring after the latch pin |03 is released is the creation oi a pressure of thou-- sands of pounds per square inch for displacing I the liquid 92 along the cylindrical bore of the ampule 9|, the time of displacement varying over a period, such as a fraction of a second, because of the small size of ghe oriilce Hpreventing any possibility of instantaneous discharge of the liquid. The higher the pressure, of course, the shorter will be the displacement time.

In my mention of thousands of pounds per square inch pressure being created, I do not wish to infer that pressures below a thousand pounds per square inch are unsuitable. .I have'found that forcertain types of hypodermic injection, pressures in excess of 30 atmospheres, or about 400 pounds per square inch, are sullicient. Pressures vbelow this level. however, are below the level of time to spray the injecting liquid over the en' y tire surface of the gums by moving' the injector relative to the gums while injection is taking place. f y

One of the most important results of the use o! my hypodermic injectoris the elimination of the v possibility of infection from unsterile needles,

(ill

utility. as they do not produce thedesiredpenetration of the liquid through the skin, with any assurance of accurate control of dosage and Aoi' administration. I

With a pressure of 10.000 pounds per square inch, liquid displacement through an orlceof .004 inch can penetrate most any animal tissue to a depth of 4 inches. Accordingly, if vit is desirable tn penetrate to a less depth, less pressure is required.

I am able to secure a relatively great pressure in pounds per square inch'with a relatively light spring |02, because the plunger end 91 is relatively small in area. The one shown on the draw'- ing is approximately /n" in diameter, which and from openings formed in the tissue which provide an entrance for bacteria.

I't is thus obvious that a predetermined high pressuremay be secured to effect a predetermined force of ejectionA of the liquid and a resultant control of dosage and administration. Unsuccessful attempts have heretofore been made to .accomplish hypodermic injection. I have found it necessaryv to provide an injector capable of exerting at least 400 pounds' per square inch on the `liquid `in `order to force it from the discharge orii-loe 93 with suillcient force to remain in the form of 'a stream of liquid which passes 1 through the epidermis without merely striking it and being deflected by it.

When a force of this magnitude, or greater. is produced by impact and/or by spring or compressed air or the like, or by any other means, then injection to a hypodermic position is pos- 3. A hypodermic injector for use with anl amsible with assured precision in dosage. By the use of a fine orifice of a few thousandths of an inch, such high pressure exerted on the liquid confines it to a fine, stream-like form, so that it all passes through the skin to the tissue therebeneath without stray droplets at the edges of the stream being deflected by the skin and thereby failing to enter to the desired subcutaneous position. The force of ejection may be predetermined by the proper selection of springs and design of the structural elements of the injector, as well as many other variable factors.

Various modifications, such as those illustrated, and others, can be made in my* hypodermic injector without departing from the real spirit and purpose of my invention. It is my intention, therefore, to cover by my claims any Amodiiied forms of structure or use of mechanical equivalents which may be reasonably included within their scope.

. I claim as my invention:

1. A hypodermic injector for use with an ampule having a blunt end with a minute discharge orifice therein, a holder having provision at one end thereof for removably and xedly holding said ampule in such a way that the blunt end thereof may be operatively positioned adjacent to and externally of tissue into which an injection is to be made, said ampule having a bore adapted to be filled with liquid to be injected into said tissue and a lfollower in said bore, said holder having a plunger arranged ,to strike said follower and impart thereto a sharp blow,

l energy-storing means for propelling said plunggy-storing means to said follower for ejecting said liquid under high pressure from said orifice.

2. A hypodermic injector for use with an ampule having a blunt end with a minute discharge orifice therein, a holder having provision at one end thereof for removably and iixedly holding said ampule in such a way that the blunt end thereof may be operatively positioned adjacent to and externally of tissue into which an injection is to be made, said ampule having a bore adapted to be filled with liquid to be injected into said tissue and a follower` in said bore, said holder having a plunger arranged to strike said follower and impart thereto a sharp blow, energy-storing means for propelling said plunger to strike said follower, manually operated provisions by means of which said energy-storing means may be charged, a latch for holding said plunger and energy-storing means in cocked position, said latch including a manually operable member extending transversely of said holder and projecting laterally therefrom, said latch upon actuation of said manually operable member being adapted to suddenly release said plunger so as to transmit energy stored in said energy-storing means to said follower for ejecting said liquid under high pressure from said orifice, the mass of said plunger being many times greaterfthan that of said liquid and follower.

pule having a blunt end with a minute discharge orifice therein, said holder having provision at one end thereof for removably and flxedly'holding said ampule in such a way that the blunt end thereof may be operatively positioned adjacent to and externally of tissue into which an injection is to be made, said ampule having a bore adapted to be nlled with liquid to be injected into said tissue and a follower in said bore, said holder having a plunger arranged to strike said follower and impart thereto a sharp blow, energy-storirig means for propelling said plunger to strike said follower, manually operated provisions by means of which said energy-storing means may be charged, a latch for holding said plunger and energy-storing means in cocked position, said latch including a manually operable member to release said plunger so as to transmit energy stored in said energy-storing means to said follower for ejecting said liquid under high pressure from said orifice.

4." A hypodermic'injector for use with an ampule having a blunt end with a minute discharge orifice therein, said holder having provision at one end thereof for removably and flXedly holding said ampule inisuch a way that the blunt end thereof may be operatively positioned adjacent to and externally of tissue into which an injection is to be made, said ampule having a bore adapted to be lled with liquid to be injected into said tissue and a follower in said bore, said holder having a plunger arranged to strike said follower and impart thereto a sharp blow, energy-storing means for propelling said plunger to strike said follower, manually operated provisions by means of which said energy-storing means may 'be charged, a latch for holding said plunger and energy-storing means in cocked position, said latch including a manually operable member tov release saidl plunger so as to transmit energy stored in said energy-storing means to said follower lfor ejecting said liquid under high pressure from said oriflce, the mass of said plunger being many times greater than that of said liquid and follower.

l 5. A hypodermic injector comprising an ampule having a, blunt end with a minute discharge orice therein of the order of .001 inches, a holder having provision at one end thereof for removably and xedly holding said ampule in such a way that the blunt end thereof may be operatively positioned against and externally of tissue into which an injection is to be made, said ampule having a bore adapted to be lled with liquid to be injected into said tissue and a follower in said bore, said holder having a plunger arranged to strike said follower and impart thereto a sharp blow, energy-storing means fof propelling said plunger to strike said follower?r provisions by means of which said energy-storing means may be charged, a latch for holding said plunger and energy-storing means in cocked position, a manually operable member adapted suddenly to release said plunger so as to transmit energy stored in said energy-storing means to said follower for ejecting a stream of said liquid from said orce under a pressure sufficiently high to penetrate said tissue, the mass of said plunger being many times greater than that of said liquidand follower. 

